The present invention relates generally to mobility management of a mobile subscriber unit operable in a microcellular communication network, such as a Digital Electronic Cordless Telephone (DECT) system or other Private Telephone Network (PTN). More particularly, the present invention relates to a method, and associated apparatus, for facilitating communications to and from the mobile subscriber unit pursuant to the microcellular communication network when the mobile subscriber unit roams into an area encompassed by a communication network other than the xe2x80x9chomexe2x80x9d microcellular communication network in which the mobile subscriber unit is regularly registered.
The microcellular communication networks are interfaced with a macrocellular communication network, such as a Global System for Mobile communications (GSM) or other Public Land Mobile Network (PLMN). Wide-area, mobility management functions existent in the macrocellular communication network are utilized by the microcellular communication network to provide wide-area mobility management to the microcellular communication network. Wide-area mobility of the mobile subscriber unit is permitted as the wide-area mobility management functions of the macrocellular communication network are used to facilitate the communication with the mobile subscriber unit. When the mobile subscriber unit roams beyond an area encompassed by the microcellular communication network in which the mobile subscriber unit is regularly registered, calls can still be routed to and from the mobile subscriber unit.
When the macrocellular communication network is formed of a GSM network, a mobility server positioned in the microcellular communication network is coupled to the GSM network and appears to the GSM network as a mobile services switching center (MSC) thereof. The wide-area, mobility management functions are used by the mobility servers of both the subscriber unit""s xe2x80x9chomexe2x80x9d network and the xe2x80x9cvisitedxe2x80x9d network into which the subscriber unit roams thereby to provide wide-area mobility to the mobile subscriber unit.
Communications between the microcellular and macrocellular communication networks are also permitted to be effectuated by way of the Internet. Data to be communicated between the networks is encapsulated according to-an Internet protocol, or the like.
Advancements in the fields of electronics and communications have permitted the introduction and commercialization of many new types of communication systems. Information can be affordably communicated to locations and in manners previously not possible or affordable.
The field of cellular telephony is exemplary of a communication system that has been made possible due to such advancements. A fixed, wireline connection is not required between a transmitting station and a receiving station in a cellular, or other radiotelephonic, communication system to effectuate communications between the stations. Because a xe2x80x9cwirelessxe2x80x9d connection is formed between the transmitting station and the receiving station, use of such a communication system is particularly advantageous to effectuate communications when a wireline connection cannot be conveniently or practically formed.
Various different types of cellular, and other radiotelephonic, communication systems have been implemented and others have been proposed. In many parts of the world, for instance, macrocellular communication networks have been installed. Such networks permit mobile subscriber units positioned anywhere within the area encompassed by the macrocellular networks to communicate pursuant to the macrocellular communication network. A macrocellular communication network typically includes a large number of base stations positioned at spaced-apart locations throughout a geographic area. As a mobile subscriber unit moves throughout the geographical area, communications with the mobile subscriber unit are xe2x80x9chanded-offxe2x80x9d to successive ones of the base stations. In one type of cellular communication system, a Global System for Mobile (GSM) communications system, control circuitry, including mobile services switching centers (MSCs) and base stations controllers (BSCs), controls communications between the base stations and the mobile subscriber unit. And, location registers, including a home location register (HLR) associated with the mobile subscriber unit, maintain a registry of the positioning of the mobile subscriber unit in a network.
Microcellular communication networks have also been developed and implemented. A Digital Electronic Cordless Telephone (DECT) system is exemplary of a microcellular communication network. A microcellular communication network, analogous to a macrocellular communication network, also permits wireless communications to be effectuated with a mobile subscriber unit. The area encompassed by a microcellular communication network is, however, typically much smaller than the area encompassed by a macrocellular communication-network.
The costs associated with a microcellular communication network are generally less than the costs associated with a macrocellular communication network. However, because microcellular communication networks generally encompass limited areas, a single business, or other operator, might be required to construct more than one microcellular communication network to encompass a desired area in which microcellular communications are to be permitted.
For instance, a microcellular communication network might be constructed to provide microcellular communication coverage encompassing a single building. A mobile subscriber unit regularly registered to communicate pursuant to the microcellular communication network must be within the building, i.e., the area encompassed by the microcellular communication network, to communicate therethrough.
It is sometimes desirable to permit a mobile subscriber unit, regularly registered in one microcellular communication network (the xe2x80x9chomexe2x80x9d network), also to communicate in another microcellular communication network (the xe2x80x9cvisitedxe2x80x9d network). For instance, a business might have separate office locations, requiring separate microcellular networks to be installed for each of the separate office locations. It is sometimes desirable, in such instances, to permit personnel regularly located at one of the office locations to be able to communicate by way of a microcellular communication network even when the personnel are temporarily positioned at the other one of the office locations.
By providing communication links between the separate microcellular networks, registration, and other, information pertaining to the mobile subscriber unit stored at the xe2x80x9chomexe2x80x9d microcellular communication network can be used to permit communications with the mobile subscriber unit, even when the mobile subscriber unit is positioned in an area encompassed by the xe2x80x9cvisitedxe2x80x9d microcellular communication network.
Various proposals have been set forth to form communication links between microcellular networks by way of a macrocellular communication network. Such proposals, however, have generally been set forth for purposes of call control and not for purposes of mobility management. Viz. existing proposals for intercoupling the networks have not generally pertained to providing wide-area mobility to mobile subscriber units of microcellular communication networks.
Additionally, existing proposals generally require direct connections between the microcellular and macrocellular communication networks. As the operators of the macrocellular and microcellular communication networks might well be different entities, the conventional requirement for direct connections between the microcellular communication networks might sometimes be problematical.
A manner by which better to provide wide-area mobility to a mobile subscriber unit to increase the mobility permitted of the mobile subscriber unit would be advantageous.
Additionally, a manner by which to provide for the communication of mobility management information between a microcellular and macrocellular communication network without requiring direct connections therebetween would also be advantageous.
It is in light of this background information related to mobility management in a cellular communication system that the significant improvements of the present invention have evolved.
The present invention advantageously provides a method, and associated apparatus, for facilitating communications to and from a mobile subscriber unit operable in a microcellular communication network when the mobile subscriber unit roams into an area encompassed by a xe2x80x9cvisitedxe2x80x9d microcellular communication network other than the xe2x80x9chomexe2x80x9d network in which the mobile subscriber unit is regularly registered.
Wide-area mobility management functions available in a macrocellular network are provided to microcellular networks by coupling the microcellular networks to the macrocellular network. Wide-area mobility is thereby provided to a mobile subscriber unit operable in a microcellular communication network. The wide-area management functions provided to the microcellular communication network permits a mobile subscriber unit to communicate by way of a microcellular communication network even when it roams into an area encompassed by a xe2x80x9cvisitedxe2x80x9d network.
When the macrocellular communication network is formed of a Global System for Mobile communications (GSM) network, the microcellular communication networks include the mobility servers which appear, to the GSM network, to be mobile services switching centers (MSCs) of the GSM network. Mobility management normally provided to the mobile services switching centers of the GSM network are provided to the mobility servers of the microcellular networks. Signaling between the mobility server and the macrocellular communication network permits, for example, calls to be placed to and from a mobile subscriber unit when the subscriber unit roams beyond the microcellular communication network in which the subscriber unit is regularly registered. Location updating of the position at which the subscriber unit roams is similarly also effectuated.
In one aspect of the present invention, location information related to the position of a mobile subscriber unit is updated when the mobile subscriber unit roams into an area encompassed by a microcellular communication network other than the network in which the subscriber unit is regularly registered. A mobility server of such xe2x80x9cvisitedxe2x80x9d microcellular network receives indications of the positioning of the subscriber unit and provides information indicative thereof to a home location register (HLR) of the macrocellular communication network. The home location register (HLR) provides the visited mobility server with subscriber data related to the mobile subscriber unit and orders the xe2x80x9chomexe2x80x9d mobility server of the subscriber unit""s home network to deregister the subscriber unit therefrom.
In an another aspect of the present invention, calls originated at a Public Switched Telephone Network (PSTN) to be terminated to a mobile subscriber unit of the xe2x80x9chomexe2x80x9d microcellular communication network are routed to the subscriber unit when the subscriber unit roams beyond the xe2x80x9chomexe2x80x9d network and into a xe2x80x9cvisitedxe2x80x9d network. In one exemplary routing method, the call is routed via the home microcellular communication network to a gateway mobile services switching center (GMSC) of the macrocellular communication network, and the GMSC interrogates the home location register of the macrocellular network to obtain routing information to route the call to the roaming, subscriber unit. The HLR requests and receives information from the mobility server of the xe2x80x9croamingxe2x80x9d microcellular network. Such information is provided to the GMSC, and the call is routed to the mobile subscriber unit, to be terminated thereat.
In another aspect of the present invention, a call originated at a roaming, subscriber unit is routed to a subscriber, unit registered in the macrocellular communication network. And, in yet another aspect of the present invention, calls are placed between a mobile subscriber unit positioned in a xe2x80x9chomexe2x80x9d microcellular network to a mobile subscriber unit roaming in a xe2x80x9cvisitedxe2x80x9d microcellular communication network. And, in yet another aspect of the present invention, the mobile subscriber unit forms a dual-mode subscriber unit, operable in both a microcellular network and a macrocellular network. Calls are placed, or received, by the subscriber unit when the subscriber unit is positioned in its xe2x80x9chomexe2x80x9d microcellular network, a visited microcellular network, or within an area encompassed only by the macrocellular network.
The present invention further advantageously permits communications between the microcellular and macrocellular communication networks by way of an Internet communication channel. Mobility management information, for example, is encapsulated according to an Internet protocol, or the like, and thereafter communicated by way of the Internet forming a connection between the microcellular and macrocellular communication networks. Because communications between the microcellular and macrocellular communication networks are effectuated by way of the Internet, direct connections between the separate networks are not required. The Internet, already existent and readily accessible, can thereby be utilized both to facilitate data communications and also telephony communications.
In these and other aspects, therefore, mobility-enhancing apparatus for a first mobility server facilitates communication with a mobile subscriber unit. The mobile subscriber unit is operable in a first microcellular communication network of a communication system having a macrocellular communication network and at least the first microcellular communication network. The first microcellular communication network includes the first mobility server. The mobility-enhancing apparatus facilitates communication with the mobile subscriber unit, operable in the first microcellular communication network, in a communication network other than the first microcellular communication network. A storage device stores location information representative of positioning of the mobile subscriber unit. A mobility manager is coupled to the storage device and to the macrocellular network. The mobility manager at least updates the location information stored in the storage device to indicate whether the mobile subscriber unit is positioned within range of the first microcellular communication network. The mobility manager further receives macrocellular network-generated data related to the mobile subscriber unit, and the network-generated data is used for the updating of the location information.